【摘要】托福考试主要是测试同学们的听力，阅读，写作及口语，下面针对托福阅读中的难点，环球网校托福频道小编为大家整理了一些应试技巧，希望对大家有帮助!
(托福阅读：TPO阅读单词语境记忆方法详解，由环球网校托福频道整理!)
Perceptions of the visible world were greatly altered by the invention of photography in the middle of the nineteenth century. In particular, and quite logically, the art of painting was forever changed, though not always in the ways one might have expected. The realistic and naturalistic painters of the mid- and late-nineteenth century were all intently aware of photography—as a thing to use, to learn from, and react to.
Unlike most major inventions, photography had been long and impatiently awaited. The images produced by the camera obscura, a boxlike device that used a pinhole or lens to throw an image onto a ground-glass screen or a piece of white paper, were already familiar—the device had been much employed by topographical artists like the Italian painter Canaletto in his detailed views of the city of Venice. What was lacking was a way of giving such images permanent form. This was finally achieved by Louis Daguerre (1787-1851), who perfected a way of fixing them on a silvered copper plate. His discovery, the "daguerreotype," was announced in 1839.
A second and very different process was patented by the British inventor William Henry Talbot (1800-1877) in 1841. Talbot's "calotype" was the firstnegative-to-positive process and the direct ancestor of the modern photograph. The calotype was revolutionary in its use of chemically treated paper in which areas hit by light became dark in tone, producing a negative image. This "negative," as Talbot called it, could then be used toprint multiple positive images on another piece of treated paper.
The two processes produced very different results. The daguerreotype was a unique image that reproduced what was in front of the camera lens in minute, unselective detail and could not be duplicated. The calotype could be made in series, and was thus the equivalent of an etching or an engraving. Its general effect was soft edged and tonal.
词汇解析：
perception n. 看法;感知
alter v. 更改
logical adj. 逻辑的;合乎逻辑的
intent adj. 坚决的;专注的
react v. 作出反应;起不良反应;反抗
impatient adj. 无耐心的
topographical adj. 地形的
permanent adj. 永久的;不断发生的
silver n. 银;银器
patent n. & v. & adj. 专利;得到...专利;显而易见的强调
ancestor n. 祖先;物种原型
multiple adj. & v. 多功能的;倍数
reproduce v. 复制;重演
duplicate v. & n. 复制;复制品
etch v. 凿刻;铭刻
engrave v. 刻上
tonal adj. 声调的
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